In one conventional technique, a plurality of versions of image data obtained by imaging with different lengths of exposure time are combined to generate dynamic-range-expanded image data (i.e., HDR image data). However, since HDR image data has a very wide dynamic range of, for example, 20-bit or the like, many of the existing display devices having a relatively narrow dynamic range of, for example, 8-bit or the like can not display HDR image data as it is. So, the dynamic range of HDR image data has needed to be converted to the dynamic range of the existing display devices.
One example of a method for converting the dynamic range of HDR image data is to convert a high dynamic range (HDR) image into a low dynamic range (LDR) image, as described in Patent Document 1.
Methods for converting an HDR image into a high-contrast LDR image is commonly called “tone mapping” or “dynamic range compression.” These methods perform dynamic range compression while maintaining good color reproducibility from dark area (shadow) to bright area (highlight).
[Prior Art References]
[Patent Documents]
[Patent Document 1] JP-A-2005-284534